(1) Technical Field of the Invention
The present invention relates to an optical disc recording apparatus and recording power control method that prevent an increase of jitter and realize stability in high-speed recording when data is recorded on an optical disc.
(2) Description of the Related Art
A phase change optical disc performs recording using reversible phase change between amorphous and crystal. A high output laser beam is irradiated onto a phase change film which is heated to a temperature equal to or higher than the melting point and is then quenched, and thus an amorphous mark is formed. A laser beam at a temperature between the crystallizing temperature and the melting point is irradiated onto the formed mark which is crystallized and thus erased. In the case of overwriting, the mark is once erased before data recording.
Recently, the recording speed of a phase change optical disc such as a DVD-RAM has been increased. Along with the increase in recording speed, the time period for the crystallization to erase the mark decreases in overwriting, and jitter is likely to occur due to an incomplete erasure after overwriting, because of an increase of the difference of the recording linear velocity between the inner and outer circumferences of the disc in CAV recording or other reasons. Thus, it is necessary to more accurately set an erasing power to erase the mark.
To meet the above described requirement there have been proposed various methods of optimizing the recording power and erasing power in test writing. For example, described in Japanese Patent Application Laid-Open No. Hei 10(1998)-320777 is a technology for setting a threshold of the recording power relative to a recording medium in such a way that a mark is recorded on the recording medium by varying the recording power of the light to be irradiated onto the recording medium and detects the phase lag (corresponding to the jitter amount) between a clock signal and a signal indicating an end of the mark obtained by reproducing the recorded mark. Here, FIG. 1 of Japanese Patent Application Laid-Open No. Hei 10(1998)-320777 shows the jitter amount or information corresponding thereto (error count number).